pH Determination of Household Products
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Predict the pH value of substances & estimate the pH value by using the red cabbage juice indicator
Use the indicator to identify acidic, basic, and neutral substances found in any home
Classify household items as acids and bases
Collect and analyze data
Organize and analyze results in tables and graphs
a. Hypothesis/prediction: All items used to clean will be more like (acids/bases) because
_________ ___________________________________________________ and items used as
foods will be more like (acids/bases) because __________________________________.
b. The indicator being used is ______________________________.
c. The independent variable is _____________ and the dependent variable is _____________.
PROCEDURE
Preparation of red cabbage indicator (done by the teacher the night before)
1. Cut ½ of a cabbage into small pieces.
2. Cook cabbage in 2 liters of water for about 15 minutes
3. Separate the bluish-purple liquid from the cabbage and let it cool
Estimating pH values with red cabbage indicator – complete data table!
4. line up all substances to be tested on top of white paper
5. write each name in your data table  data table!
6. predict each substance as basic, neutral, or acidic  data table!
7. record the color of each substance to be tested - best to use color pencils!  data table!
8. observe the red cabbage indicator, record its color  data table!
9. place a labeled beaker in front of each substance to be tested
10. add about 5-10mL of red cabbage indicator to all labeled beakers
11. to the corresponding cups with indicator, add drop by drop up to 5mL of (1mL = 16 drops) the
substance to be tested & record the color change of the indicator  data table!
12. organize all cups from most acidic to most basic using as a guide the pH scale for red cabbage juice
13. estimate the pH value of each substance by using the pH scale for red cabbage juice  record in the
data table!
14. classify each product as acid, base, or neutral  record in the data table!
15. slowly pour 2 mL of vinegar into 2 mL of baking powder and write your observations
16. add 2 mL of milk into each cup (A & B). Add 6 drops of water to cup A. After each drop, mix well &
record any change. Using vinegar, repeat the procedure with cup B and record any changes.
CLEAN UP! Pour all substances in the waste beaker & rinse each used beaker. Dry each cup & leave
everything the way you found it. Remember no traces of water on your working area or -25pts for
each member of the group.
Finding actual pH values with litmus paper
17. Get another set of samples.
18. Carefully dip the 1 piece litmus paper into each of the samples
19. Compare the colour of the litmus paper to the colours on the container
20. Write down your actual pH value in your table
Household
Prediction  Acid,
Initial color
Product
Base, Neutral
of product
1. HCl
(hydrochlo
ric acid)
2.
3.
4.
5.
6.
7.
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9.
10.
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12.
13.
14. NaOH
(Sodium
Hydroxide)
Initial color of
indicator (colour)
Final color of
Estimated pH
Actual pH
indicator (colour)
Values
Value